Suwaid bin Ghaflah reports that Sayyiduna Umar (may Allah be pleased with him) while delivering a sermon at "Jabiyah" said that the Messenger of Allah (peace and blessings be upon him) forbade (men) from wearing silk, except for an amount equal to two, three, or four fingers, and while saying this, Sayyiduna Umar (may Allah be pleased with him) also gestured with his palm.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 365
Hadith Gradingحکم دارالسلام:حديث صحيح، وسماع محمد بن جعفر من سعيد بن أبى عروبة مختلف فيه : أقبل الاختلاط أم بعده؟ خ : 5828، م: 2069